Perhaps you should try some spelling variations:
danh vai » danh sai, danh va, doanh van
doan van » doan va, hoang van, luan van
su sach » so sach, vu sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
cam tu » cam thu, nam tu, dam tu
hoa » khoa

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y ((nang xa) or (nang ma)) hoi. hieu ve cam tu va ((danh vai) or (doan van)) hoa viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((nang xa) OR (nang ma)) hoi. hieu ve cam tu va ((danh vai) OR (doan van)) hoa viet.
• Adding a wildcard symbol may retrieve word variants: su sach y ((nang xa) or (nang ma)) hoi. hieu ve cam tu va ((danh vai) or (doan van)) hoa viet*.